Shock-absorbing seat belt buckles for motor vehicles are generally known and are preferably utilized in conjunction with a seat belt pretensioner that engages on the seat belt buckle via a pull cable and that has the function to take existing belt slack out of the safety belt, and to thereby couple the passenger to the vehicle deceleration preferably early.
From WO 2006/114204 A1, for example, a shock-absorbing seat belt buckle is known which comprises an inertia mass connected to the buckle release push-button via a transmission lever. The acceleration forces acting upon the inertia mass during the tensioning process are acting in the same direction as the acceleration forces acting upon the push-button and are transmitted to the same by a transmission lever against the opening direction of the push-button. It is thereby prevented that the push-button moves in the opening direction during the belt tensioning subjected to its own inertia forces, and thereby releases the seat belt buckle unintentionally. As the inertia mass, owing to its function to generate the required inertia forces, must have a certain self-weight, and as also the transmission lever must have a certain stability for the transmission of the arising forces, both components are preferably made of a metal. Furthermore, a small gap has to be provided between the linearly guided inertia mass and the transmission lever performing a rotation, so that the path of motion can be completed without clamping. This gap, particularly in the position of the inertia mass where no inertia forces are effective, leads to an undesired metallic rattling.
It is the object of the invention to improve a shock-absorbing seat belt buckle of the above-described kind in such a way that, even in its non-operated state, no undesired rattling noises can occur.